title: Effect of hOGG1 over-expression on cisplatin resistance in esophageal squamous carcinoma cells.
abstract: OBJECTIVE
  Human 8-oxoguanine DNA glycosylase (hOGG1) is an ubiquitous protein. It initiates the DNA base excision repair (BER) pathway to repair the 8-oxoguanine lesion. This may be associated with chemotherapeutics. In this article, the effect of hOGG1 over-expression on cisplatin resistance in esophageal squamous cell carcinoma (ESCC) EC9706 and ET13 cells was investigated.
  
  
  METHODS
  Recombinant adenovirus pAd/CMV/V5-DEST-hogg1 and control adenovirus pAd/CMV/5-GW/lacZ were constructed and transferred into EC9706 and ET13 cells, respectively. The protein expression and localization were determined by Western blot and by immunofluorescence assay. The cell growth viability was determined by 3-(4,5-dimethylthiazol-2yl)-2,5 diphe-nyltetrazolium bromide (MTT) assay and clonogenic survival assay. The apoptotic cells were detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) staining and flow cytometry. The oxidative DNA damage (8-Hydroxyguanine [8-oxoG] DNA level) was semi-quantified by immunohistochemistry assay.
  
  
  RESULTS
  The over-expression of hOGG1 protein was mainly in the nucleus in hOGG1 cells. After exposure to a common chemotherapeutic agent cisplatin, hOGG1 over-expression cells exhibited longer survival ability, lower cell apoptosis, and less 8-oxoG oxidative damage, compared with vector-treated cells and no-treated cells (p<0.05).
  
  
  CONCLUSIONS
  BER pathway to repair 8-oxoG lesion may be associated with ESCC sensitivity to cisplatin, and over-expression of hOGG1 in the nucleus can repair more 8-oxoG oxidative damage. The findings implied that over-expression of hOGG1 can protect ESCC cells from cisplatin-induced apoptosis and prolong cancer cell survival time. Modulation of DNA damage repair activity in the nucleus or in the mitochondria may lead to a different approach regarding cisplatin-induced resistance to chemotherapy.
authors.affiliation: School of Medicine, Southeast University, Nanjing, People's Republic of China. dgao2@yahoo.com
authors.forename: Daqing
authors.initials: D
authors.lastname: Gao
authors.forename: Jiangwen
authors.initials: J
authors.lastname: Hu
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhang
authors.forename: Chong
authors.initials: C
authors.lastname: Gao
authors.forename: Jie
authors.initials: J
authors.lastname: Hong
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002945:Cisplatin / Q000494:pharmacology*; D045647:DNA Glycosylases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm; D004938:Esophageal Neoplasms / Q000188:drug therapy* / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D000077277:Esophageal Squamous Cell Carcinoma; D006801:Humans; D014162:Transfection
chemical_list: D000970:Antineoplastic Agents; D045647:DNA Glycosylases; C479058:oxoguanine glycosylase 1, human; D002945:Cisplatin